In order to manufacture multilayer photographic film materials of high quality and low cost, it is required that several layers be coated simultaneously at high coating speeds, and that the individual layers have a high degree of thickness uniformity including the absence of spot nonuniformities. Overcoat layers of photographic film products often contain a variety of dispersed addenda such as polymer matte beads and lubricant materials. Some of these may increase the propensity for the formation of round or comet-shaped spot nonuniformities (in thickness of the overcoat and adjacent layers) of the type called repellency spots. These repellency spots formby surface-tension driven flow in small areas during the coating process and have dimensions large enough to be seen without magnification or with up to 10.times.magnification. Surface active compounds or surfactants are added to the coating solutions of overcoat layers to prevent the formation of undesired layer thickness nonuniformities including repellency spots. When added for this purpose, they are called "coating aids".
Many surfactant compounds with a variety of chemical structures have been used as coating aids for improved layer thickness uniformity in manufacturing photographic materials. It is known that surfactant coating aids with different chemical structures exhibit different degrees of effectiveness in controlling repellency spots. Since the surfactants present in overcoat layers can also have a significant influence on surface physical properties of the multilayer photographic material after drying, mixtures of one or more coating aid surfactants with one or more other surfactants are commonly used in overcoat layers for the purpose of modifying physical properties. Although there are several surfactant mixtures widely used as coating aids for overcoat layers, there is a need for improved coating aid mixtures for improved control of repellency spots. This is especially true in the case of overcoat layers which contain alkali-soluble polymer matte beads, specifically poly(methyl methacrylatemethacrylic acid) copolymer matte compositions. The surfactant mixtures must simultaneously provide the required surface physical properties needed for each specific type of film product.